Driving tool

ABSTRACT

A driving tool includes a striking cylinder including a piston configured to be actuated by a combustion pressure of a mixed gas of compressed oxidant and fuel, a combustion chamber in which the mixed gas of compressed oxidant and fuel is to be combusted; a valve member configured to open and close communication between the striking cylinder and the combustion chamber, and a striking cylinder exhaust valve configured to open and close communication between the striking cylinder and an outside.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2018-007520 filed on Jan. 19, 2018, Japanese Patent Application No. 2018-007521 filed on Jan. 19, 2018, Japanese Patent Application No. 2018-007633 filed on Jan. 19, 2018, Japanese Patent Application No. 2018-022480 filed on Feb. 9, 2018, Japanese Patent Application No. 2018-022481 filed on Feb. 9, 2018, Japanese Patent Application No. 2018-022482 filed on Feb. 9, 2018, Japanese Patent Application No. 2018-026624 filed on Feb. 19, 2018, Japanese Patent Application No. 2018-084498 filed on Apr. 25, 2018, Japanese Patent Application No. 2018-084499, filed on Apr. 25, 2018, Japanese Patent Application No. 2018-084500 filed on Apr. 25, 2018, and Japanese Patent Application No. 2018-084501 filed on Apr. 25, 2018, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a driving tool configured to combust a mixed gas of compressed oxidant and fuel and to be driven by a combustion pressure.

BACKGROUND

A driving tool referred to as a nailing machine configured to strike a fastener such as a nail by actuating a piston with a striking cylinder by using a compressed air (compressed oxidant) as a power source and driving a driver joined to the piston has been known.

Also, a driving tool configured to strike a fastener such as a nail by combusting a mixed gas of air and fuel and actuating a striking cylinder by a combustion pressure has been known. In the gas combustion type driving tool, the mixed gas of which a pressure has been increased in advance is combusted to further increase the combustion pressure. However, since the mixed gas of which a pressure has been increased is generated, when the compressed air is supplied to a combustion chamber, the striking cylinder is actuated by a pressure of the compressed air before the mixed gas is combusted.

Therefore, a driving tool including a head valve mechanism configured to openably and closably partition a combustion chamber in which a mixed gas of compressed air and fuel is to be combusted and a striking cylinder has been suggested (for example, refer to Patent Document 1).

Also, in the driving tool configured to actuate the striking cylinder by the combustion pressure, in order to exhaust a gas remaining in the combustion chamber after a piston of the striking cylinder is actuated, the combustion chamber is provided with an exhaust port. Further, a check valve is provided at a part at which the combustion chamber and the striking cylinder are partitioned therebetween, and the gas in the striking cylinder is sent from the check valve to the combustion chamber, so that the gas is exhausted from the exhaust port of the combustion chamber (for example, refer to Patent Document 2).

Patent Document 1: JP-A-S51-58768

Patent Document 2: Japanese Patent No. 4,935,978B

In the driving tool configured to actuate the striking cylinder by the combustion pressure, the mixed gas of compressed air and fuel is combusted in the combustion chamber to open communication between the striking cylinder and the combustion chamber by the head valve mechanism, and the high temperature and high pressure gas flows from the combustion chamber into the striking cylinder, so that when a pressure in the combustion chamber is lowered, the head valve mechanism is closed. For this reason, while the piston returns from a bottom dead point position to a top dead point position, it is not possible to exhaust the gas in the striking cylinder from the exhaust port provided to the combustion chamber to an outside, so that it is difficult to securely return the piston to the top dead point position.

Therefore, the check valve is provided at the part at which the combustion chamber and the striking cylinder are partitioned therebetween, and the gas in the striking cylinder is sent from the check valve to the combustion chamber, so that it is possible to exhaust the gas in the striking cylinder from the exhaust port provided to the combustion chamber to the outside. However, according to the configuration where the check valve is provided at the part at which the combustion chamber and the striking cylinder are partitioned therebetween, it is necessary to secure a pressure difference between the combustion chamber and the striking cylinder so as to open the check valve. For this reason, when the pressure in the striking cylinder is lowered as the gas in the striking cylinder is exhausted from the exhaust port of the combustion chamber to the outside through the check valve, the check valve may be closed before the pressure in the striking cylinder is lower to an atmospheric pressure, depending on the pressure in the combustion chamber. In this case, it is not possible to securely return the piston to the top dead point position due to a residual pressure in the striking cylinder. Also, the check valve is provided, so that the structure becomes complicated, and the combustion chamber is enlarged so as to secure a volume of the combustion chamber.

SUMMARY

The present disclosure has been made in view of the above situations, and an object thereof is to provide a driving tool capable of exhausting a gas in a striking cylinder without via a combustion chamber.

One aspect of the present disclosure provides a driving tool comprising: a striking cylinder including a piston configured to be actuated by a combustion pressure of a mixed gas of compressed oxidant and fuel; a combustion chamber in which the mixed gas of compressed oxidant and fuel is to be combusted; a valve member configured to open and close communication between the striking cylinder and the combustion chamber; and a striking cylinder exhaust valve configured to open and close communication between the striking cylinder and an outside.

In the above configuration, the mixed gas of compressed oxidant and fuel is combusted in the combustion chamber, communication between the striking cylinder and the combustion chamber is opened by the valve member, and the high temperature and high pressure gas flows from the combustion chamber into the striking cylinder, so that the piston is moved from the top dead point position to the bottom dead point position and a striking operation is thus performed. When communication between the striking cylinder and the combustion chamber is closed by the valve member as the pressure in the combustion chamber is lowered, the gas in the striking cylinder is exhausted from the striking cylinder to the outside by the exhaust valve while the piston returns from the bottom dead point position to the top dead point position.

In the above configuration, even when communication between the striking cylinder and the combustion chamber is closed by the valve member, it is possible to exhaust the gas in the striking cylinder to the outside by the exhaust valve while the piston returns from the bottom dead point position to the top dead point position, so that it is possible to securely return the piston to the top dead point position. Also, it is not necessary to provide a check valve at a part at which the combustion chamber and the striking cylinder are partitioned therebetween, and it is possible to exhaust the gas in the striking cylinder to the outside, irrespective of the pressure in the combustion chamber, to securely return the piston to the top dead point position, to simplify the structure because it is not necessary to provide the check valve, and to suppress the combustion chamber from being enlarged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration view of main parts depicting an example of a nailing machine of an embodiment.

FIG. 2 is an overall configuration view depicting an example of the nailing machine of the embodiment.

FIG. 3 is an overall configuration view depicting an example of the nailing machine of the embodiment.

FIG. 4 is a configuration view of main parts depicting an example of the nailing machine of the embodiment and an operation example.

FIG. 5 is a configuration view of main parts depicting an example of the nailing machine of the embodiment and an operation example.

FIG. 6 is a configuration view of main parts depicting an example of the nailing machine of the embodiment and an operation example.

FIG. 7 is a configuration view of main parts depicting an example of the nailing machine of the embodiment and an operation example.

DETAILED DESCRIPTION

Hereinafter, an embodiment of a nailing machine, which is an example of the driving tool of the present disclosure, will be described with reference to the drawings.

<Configuration Example of Nailing Machine of Embodiment>

FIG. 1 is a configuration view of main parts depicting an example of a nailing machine of an embodiment, and FIGS. 2 and 3 are overall configuration views depicting an example of the nailing machine of the embodiment. Also, FIGS. 4 to 7 are configuration views of main parts depicting an example of the nailing machine of the embodiment and an operation example.

A nailing machine 1A of the embodiment includes a main body part 10 and a handle part 11 extending from the main body part 10 and configured to be gripped by a hand. The nailing machine 1A includes a nose part 12 provided at one side of the main body part 10 and configured to strike out a fastener therefrom. In below descriptions, considering a using aspect of the nailing machine 1A, the side at which the nose part 12 is provided is referred to as ‘lower side’, and a side opposite to the side at which the nose part 12 is provided is referred to as ‘upper side’. Also, a side at which the handle part 11 is provided is referred to as ‘rear side’ and a side opposite to the side at which the handle part 11 is provided is referred to as ‘front side’.

The nailing machine 1A includes a tank mounting part 13, to which a fuel tank (not shown) having fuel filled therein is detachably mounted and which is provided substantially in parallel with the handle part 11 below the handle part. Also, the nailing machine 1A includes a magazine 14 configured to share fasteners with the nose part 12 and provided below the tank mounting part 13. Also, the nailing machine 1A includes an air plug 15 to which an air hose, to which compressed air (compressed oxidant) is to be supplied from a supply source such as an air compressor, is connected and which is provided to the tank mounting part 13, in the embodiment.

Also, the nailing machine 1A includes an operation trigger 16 configured to actuate the nailing machine 1A and provided to the handle part 11, and a battery mounting part 18 to which a battery 17 becoming a power supply of the nailing machine 1A is to be mounted and which is provided to the handle part 11.

The nailing machine 1A includes a striking cylinder 2 configured to be actuated by a combustion pressure of a mixed gas of compressed air and fuel, a combustion chamber 3 in which the mixed gas of compressed air and fuel is to be combusted, a head valve 4 configured to open and close communication between the striking cylinder 2 and the combustion chamber 3, and a valve support member 5 configured to support the head valve 4.

The striking cylinder 2 is an example of the striking mechanism, and includes a driver 20 configured to strike out a fastener supplied from the magazine 14 to the nose part 12 and a piston 21 to which the driver 20 is provided. The striking cylinder 2 has a cylindrical space in which the piston 21 can be slid, and is configured so that the driver 20 is to move along the extension direction of the nose part 12 by a reciprocal operation of the piston 21.

The striking cylinder 2 has a piston position restraint part 2 a provided at a peripheral edge of an upper end and formed to have a tapered shape of which a diameter increases upward. When the piston 21 is moved upward, a piston ring 21 a provided on an outer peripheral surface of the piston 21 is engaged to the piston position restraint part 2 a, so that a top dead point position of the piston 21 is defined. In the meantime, the engagement of the piston 21 with the piston position restraint part 2 a is released by a force of pushing the piston 21 by a combustion pressure, so that the piston 21 can move by the combustion pressure.

Also, the striking cylinder 2 includes a buffer material 22 with which the piston 21 is to collide. The buffer material 22 is configured by an elastic member and is provided at a lower part of the striking cylinder 2. In the striking cylinder 2, the piston 21 having moved downward by an operation of striking out a fastener collides with the buffer material 22, so that movement ranges of the driver 20 and the piston 21 are restrained.

The combustion chamber 3 is provided above the striking cylinder 2 along axial directions of the driver 20 and the piston 21, which are an axial direction of the striking cylinder 2. The striking cylinder 2 and the combustion chamber 3 are partitioned by a partitioning part 50, and the partitioning part 50 is provided with a striking cylinder inlet 51 through which high temperature and high pressure combusted air is to pass. The striking cylinder inlet 51 is an example of the striking mechanism inlet, and is configured by forming a circular opening on axes of the driver 20 and the piston 21, which are the axial direction of the striking cylinder 2.

The combustion chamber 3 has the valve support member 5 provided around the striking cylinder inlet 51, and a ring-shaped space formed around the valve support member 5.

The head valve 4 is an example of the valve member, and is configured by a cylindrical metal member. As shown in FIGS. 6 and 7, the head valve 4 has a circular planar valve surface 40 of which a lower end face in an axial direction of the cylinder is closed. The head valve 4 has a configuration where a diameter of the valve surface 40 is larger than the striking cylinder inlet 51, and the striking cylinder inlet 51 is closed in a state where the valve surface 40 is in contact with the partitioning part 50.

The head valve 4 has a first seal part 41 and a second seal part 42. The first seal part 41 is an example of the seal part, is provided on an outer periphery of the valve surface 40 in the axial direction, which is a moving direction of the head valve 4, and is attached with a first seal material 41 a. The first seal material 41 a is configured by a metal ring referred to as a piston ring. The first seal part 41 has a circumferential groove in which the first seal material 41 a is fitted. When the first seal material 41 a is attached to the first seal part, the first seal material 41 a protrudes from a circumferential surface by a predetermined amount. In the case of the first seal part 41 of the embodiment, the two first seal materials 41 a are attached along the axial direction of the head valve 4.

The second seal part 42 is an example of the seal part, is provided on the outer periphery of the head valve 4 with being spaced from the first seal part 41 by a predetermined distance along the axial direction of the head valve 4, and is attached with a second seal material 42 a. The second seal material 42 a is a so-called O-ring made of an elastic body such as rubber. The second seal part 42 has a circumferential groove in which the second seal material 42 a is fitted. When the second seal material 42 a is attached to the second seal part, the second seal material 42 a protrudes from a circumferential surface by a predetermined amount.

The head valve 4 has a configuration where the first seal part 41 and the second seal part 42 protrude outward from the circumferential surface of the head valve 4 and a diameter of the second seal part 42 is larger than a diameter of the first seal part 41. The second seal part 42 has an actuation surface 43 that is a surface facing the first seal part 41 and is to be pushed by a high temperature and high pressure gas. The actuation surface 43 is a ring-shaped surface.

The head valve 4 is configured to be urged in a direction of the partitioning part 50 by a spring 44. The spring 44 is an example of the urging member, and is configured by a coil spring. An axis of the spring 44 is provided on the axes of the driver 20 and the piston 21, which are on the axis of the striking cylinder 2, i.e., is provided coaxially with the head valve 4 and the striking cylinder inlet 51. The spring 44 is introduced into a concave part 45 having an open upper and formed in the head valve 4 along the axial direction, which is a moving direction of the head valve 4, so that the head valve 4 and a part of the spring 44 are arranged with overlapping each other. This arrangement is referred to as ‘overlap arrangement’. Also, in order for the spring 44 to be introduced into the concave part 45 of the head valve 4, a diameter of the spring 44 is made to be smaller than the head valve 4 and the striking cylinder 2.

A force of pushing the head valve 4 by the spring 44 is a force of keeping a contact state of the valve surface 40 with the partitioning part 50 in a state where the high temperature and high pressure gas is not applied to the actuation surface 43.

The head valve 4 is supported to be moveable by the valve support member 5.

The valve support member 5 is an example of the valve support member and is configured by a cylindrical metal member. As shown in FIGS. 6 and 7, in the embodiment, the valve support member 5 has the partitioning part 50 integrally provided at an axial lower part of the cylinder. When the head valve 4 is put in the cylindrical inner space, the first seal material 41 a of the first seal part 41 and the second seal material 42 a of the second seal part 42 of the head valve 4 are sliding contacted to the valve support member 5. The valve support member 5 has different inner diameters at parts to which the first seal material 41 a of the first seal part 41 and the second seal material 42 a of the second seal part 42 of the head valve 4 are sliding contacted, in conformity to the respective seal parts.

When the head valve 4 is put in the valve support member 5, an actuation space 52 is formed between the first seal part 41 and second seal part 42 of the head valve 4 and an inner surface of the valve support member 5. The actuation space 52 is an annular space.

The valve support member 5 has a head valve inlet 53 for connecting the combustion chamber 3 and the actuation space 52. The head valve inlet 53 is configured by providing an opening penetrating the valve support member 5 in the vicinity of the first seal part 41 in a state where the valve surface 40 of the head valve 4 is in contact with the partitioning part 50. The head valve inlet 53 is formed on a side surface of the valve support member 5, so that a flow path connecting the combustion chamber 3 and the actuation space 52 becomes simple and an increase in inflow resistance can be prevented.

As shown in FIG. 6, the head valve inlet 53 is coupled to the actuation space 52 in the state where the valve surface 40 of the head valve 4 is in contact with the partitioning part 50, i.e., in the state where the striking cylinder inlet 51 is closed by the head valve 4.

In contrast, when the high temperature and high pressure gas is applied to the actuation surface 43 of the head valve 4 and the head valve 4 is thus moved upward, as shown in FIG. 7, the striking cylinder inlet 51 is opened and the head valve inlet 53 is coupled to the striking cylinder inlet 51.

The air to pass through the head valve inlet 53 is the high temperature and high pressure air generated by combusting the mixed gas of compressed air and fuel in the combustion chamber 3. Since the high temperature and high pressure gas has lower viscosity than the ordinary temperature and pressure air, the increase in resistance against the gas flow is suppressed even though an opening area of the head valve inlet 53 is small.

The first seal part 41 has the first seal material 41 a provided on the outer periphery thereof, and the first seal material 41 a is in contact with the inner surface of the valve support member 5. Since the first seal material 41 a is fitted in the groove, a part to be exposed to the actuation space 52 is suppressed to the minimum.

The second seal part 42 has the second seal material 42 a provided on the outer periphery thereof, and the second seal material 42 a is in contact with the inner surface of the valve support member 5. Since the second seal material 42 a is fitted in the groove, a part to be exposed to the actuation space 52 is suppressed to the minimum.

The valve support member 5 has a buffer material 54 with which the head valve 4 is to collide. The buffer material 54 is configured by an elastic member and is provided at an upper part of the head valve 4. The head valve 4 having moved due to the high temperature and high pressure gas applied to the actuation surface 43 of the head valve 4 collides with the buffer material 54 of the valve support member 5, so that a movement range of the head valve 4 is restrained. In the meantime, although the movement range of the head valve 4 is restrained by the buffer material 54, when the head valve 4 collides with the buffer material 54, a shock is absorbed by elastic deformation of the buffer material 54. Therefore, a height of the head valve inlet 53 is preferably set to be equal to or smaller than a stroke of the head valve 4. Thereby, when the head valve 4 moves up to a position at which it is to collide with the buffer material 54, the head valve 4 is not exposed to the head valve inlet 53 and the head valve inlet 53 is entirely opened. In this way, an opening amount of the head valve inlet 53 is made constant, so that it is possible to stabilize an output.

The upper opening of the combustion chamber 3 is sealed by a head part 30. The head part 30 is provided with an ignition device 31. Also, the head part 30 is provided with a fuel supply port and a compressed air supply port (not shown). Also, the buffer material 54 is provided to be in contact with the head part 30, so that the shock to be applied to the head part 30 is buffered, durability of a component is improved, a bolt for fastening the head part 30 to the combustion chamber 3 is prevented from being unfastened, and an electric noise is reduced.

The nailing machine 1A includes a blowback chamber 6 for storing the gas to return the driver 20 and the piston 21 of the striking cylinder 2. The blowback chamber 6 is provided around the striking cylinder 2 and is coupled to an inside of the striking cylinder 2 at an inlet/outlet 60 provided in the vicinity of the buffer material 22.

The nailing machine 1A has an exhaust valve 7 configured to exhaust the gas in the striking cylinder 2 and the combustion chamber 3. The exhaust valve 7 is an example of the exhaust valve, is provided at one side part of the striking cylinder 2 with respect to the extension direction of the handle part 11, and includes an exhaust piston 71 configured to be pushed by a gas introduced into the blowback chamber 6, a first exhaust valve 72 configured to open and close a striking cylinder exhaust port 23 formed in the striking cylinder 2, a second exhaust valve 73 configured to open and close a combustion chamber exhaust port 32 formed in the combustion chamber 3, and a valve rod 74 coupling the exhaust piston 71, the first exhaust valve 72 and the second exhaust valve 73.

The exhaust piston 71, the first exhaust valve 72, the second exhaust valve 73, and the valve rod 74 of the exhaust valve 7 are integrally made of metal. The exhaust valve 7 is configured so that movement of the exhaust piston 71 is to be transmitted to the first exhaust valve 72 and the second exhaust valve 73 via the valve rod 74 and the first exhaust valve 72 and the second exhaust valve 73 are thus to move in conjunction with the movement.

Also, the exhaust valve 7 includes an exhaust cylinder 75 to be coupled to the blowback chamber 6, and an exhaust flow path forming cylinder 76 to be coupled to the striking cylinder exhaust port 23 and the combustion chamber exhaust port 32. The exhaust cylinder 75 has a cylindrical space, in which the exhaust piston 71 can be slid, provided at one side part of the striking cylinder 2 with respect to the extension direction of the handle part 11, and the exhaust valve 7 is configured to move in the extension direction of the valve rod 74 by a reciprocal operation of the exhaust piston 71.

The exhaust flow path forming cylinder 76 has a cylindrical space, in which the first exhaust valve 72 and the second exhaust valve 73 can be slid, provided at one side part of the striking cylinder 2 with respect to the extension direction of the handle part 11, and extends in a moving direction of the piston 21.

The striking cylinder exhaust port 23 is an example of the exhaust port, is formed by an outer opening 23 a penetrating the exhaust flow path forming cylinder 76 and an outside and an inner opening 23 b penetrating the exhaust flow path forming cylinder 76 and the striking cylinder 2, and is configured to communicate the outside and the inside of the striking cylinder 2 via the exhaust flow path forming cylinder 76.

The inner opening 23 b of the striking cylinder exhaust port 23 is provided to face a top dead point position of the piston 21 so that the gas in the striking cylinder 2 can be exhausted to the outside by a return operation of the piston 21 from a bottom dead point position to the top dead point position. Also, the outer opening 23 a of the striking cylinder exhaust port 23 opens toward a side of the striking cylinder 2, and the outer opening 23 a and the inner opening 23 b are arranged on one line.

The combustion chamber exhaust port 32 is an example of the exhaust port, is formed by an outer opening 32 a penetrating the exhaust flow path forming cylinder 76 and the outside and an inner opening 32 b penetrating the exhaust flow path forming cylinder 76 and the combustion chamber 3, and is configured to communicate the outside and the inside of the combustion chamber 3 via the exhaust flow path forming cylinder 76. The exhaust flow path forming cylinder 76 and the combustion chamber 3 are partitioned therebetween by a wall part 76 a, except a part at which the inner opening 32 b is provided.

The outer opening 32 a of the combustion chamber exhaust port 32 opens toward a side of the striking cylinder 2, and the outer opening 32 a and the inner opening 32 b are arranged with being vertically offset in the moving direction of the second exhaust valve 73.

The first exhaust valve 72 is an example of the striking cylinder exhaust valve, has a substantially circular column shape conforming to an inner peripheral surface of the exhaust flow path forming cylinder 76, and has a pair of sealing parts 72 a, 72 b having diameters capable of slidably contacting the inner surface of the exhaust flow path forming cylinder 76 and a flow path forming part 72 c provided between the pair of sealing parts 72 a, 72 b, having a substantially circular column shape of a diameter smaller than the sealing parts 72 a, 72 b and forming a space between the flow path forming part and the inner surface of the exhaust flow path forming cylinder 76.

The second exhaust valve 73 is an example of the combustion chamber exhaust valve, has a substantially circular plate shape conforming to the inner peripheral surface of the exhaust flow path forming cylinder 76 and includes a sealing member 73 a provided on an outer peripheral surface thereof. The sealing member 73 a is configured by an O-ring, for example, and the sealing member 73 a is configured to sliding contact the inner peripheral surface of the exhaust flow path forming cylinder 76.

As shown in FIG. 1, the first exhaust valve 72 has such a configuration that when the flow path forming part 72 c is moved to a position facing the outer opening 23 a and the inner opening 23 b of the striking cylinder exhaust port 23, the outer opening 23 a and the inner opening 23 b of the striking cylinder exhaust port 23 communicate with each other by the space formed between the inner surface of the exhaust flow path forming cylinder 76 and the flow path forming part 72 c and the striking cylinder exhaust port 23 opens.

Also, when the flow path forming part 72 c is moved to the position facing the outer opening 23 a and the inner opening 23 b of the striking cylinder exhaust port 23, the upper exhaust flow path forming cylinder 76 of the flow path forming part 72 c is sealed by one sealing part 72 a and the lower exhaust flow path forming cylinder 76 is sealed by the other sealing part 72 b.

The sealing parts 72 a, 72 b are made of metal and are not provided with a sealing member such as an O-ring but implement a sealing structure by dimensions of outer diameters of the sealing parts 72 a, 72 b and an inner diameter of the exhaust flow path forming cylinder 76.

In a state where the striking cylinder exhaust port 23 is opened by the first exhaust valve 72, the second exhaust valve 73 moves to the upper of the inner opening 32 b of the combustion chamber exhaust port 32, so that the inner opening 32 b and the outer opening 32 a of the combustion chamber exhaust port 32 communicate with each other therebetween by the exhaust flow path forming cylinder 76 and the combustion chamber exhaust port 32 opens, as shown in FIG. 1.

Also, in the state where the second exhaust valve 73 has moved to the upper of the inner opening 32 b of the combustion chamber exhaust port 32, the sealing part 72 a of the first exhaust valve 72 is located below the outer opening 32 a of the combustion chamber exhaust port 32, so that the striking cylinder exhaust port 23 and the combustion chamber exhaust port 32 are sealed therebetween by the sealing part 72 a of the first exhaust valve 72.

In this way, the exhaust valve is configured by the first exhaust valve 72, the striking cylinder exhaust port 23 and the exhaust flow path forming cylinder 76, and the combustion chamber exhaust valve is configured by the second exhaust valve 73, the combustion chamber exhaust port 32 and the exhaust flow path forming cylinder 76.

Also, the first exhaust valve 72, the striking cylinder exhaust port 23 and the exhaust flow path forming cylinder 76 are provided at one side part of the striking cylinder 2, and the striking cylinder exhaust port 23 faces toward a side of the striking cylinder 2. Also, the second exhaust valve 73, the combustion chamber exhaust port 32 and the exhaust flow path forming cylinder 76 are provided at one side part of the combustion chamber 3, and the combustion chamber exhaust port 32 faces toward a side of the combustion chamber 3.

Also, the exhaust valve 7 has a buffer material 77 with which the exhaust piston 71 is to collide. The buffer material 77 is configured by an elastic member. The exhaust piston 71 collides with the buffer material 77, so that a movement range of the exhaust valve 7 is restrained.

Also, the exhaust valve 7 includes a spring 79 configured to urge the valve rod 74 in a direction in which the first exhaust valve 72 is to close the striking cylinder exhaust port 23 and the second exhaust valve 73 is to close the combustion chamber exhaust port 32. The spring 79 is an example of the urging member, is configured by a compression coil spring, in the embodiment, and is interposed between a spring receiving part 24 provided on a side surface of the striking cylinder 2 and a spring retainer 74 a attached to the valve rod 74.

The spring retainer 74 a is configured to move integrally with the valve rod 74. When the valve rod 74 is moved in a direction of compressing the spring 79 by the spring retainer 74 a, the first exhaust valve 72 opens the striking cylinder exhaust port 23 and the second exhaust valve 73 opens the combustion chamber exhaust port 32. Also, when the valve rod 74 is moved in a direction in which the spring 79 is to extend, the first exhaust valve 72 closes the striking cylinder exhaust port 23 and the second exhaust valve 73 closes the combustion chamber exhaust port 32.

The nailing machine 1A has a contact member 8 provided in the nose part 12. The contact member 8 is provided to be moveable along the extension direction of the nose part 12, and is urged by a spring 80 in a direction in which it is to protrude from the nose part 12. The contact member 8 is coupled to the exhaust valve 7 via a link 81. The link 81 is attached to a side surface of the striking cylinder 2 to be rotatable about a shaft 81 d, which is a support point, and is coupled at one end to the contact member 8. The link 81 is urged by the spring 80 such as a tensile coil spring, so that the contact member 8 rotates in the direction in which it protrudes from the nose part 12.

Also, the other end of the link 81 is coupled to the exhaust valve 7 via a long hole portion 78 formed in the valve rod 74. The long hole portion 78 is an opening extending in the moving direction of the valve rod 74 and is configured so that the valve rod 74 can move in a state where a position of the link 81 is fixed by the contact member 8.

Thereby, the link 81 rotates in conjunction with movement of the contact member 8, so that the exhaust valve 7 is actuated. Also, in the state where a position of the link 81 is fixed by the contact member 8, the link 81 and the valve rod 74 are decoupled with shapes of the link 81 and of the long hole portion 78 and the exhaust valve 7 is actuated by the gas introduced into the blowback chamber 6.

<Operation Example of Nailing Machine of Embodiment>

Subsequently, an operation of the nailing machine 1A of the embodiment is described with reference to the respective drawings. In an initial state, the operation trigger 16 is not pulled, and the contact member 8 is not pressed to a material to be struck and is located at an initial position at which it is urged by the spring 80 and protrudes from the nose part 12.

In a state where the contact member 8 is located at the initial position, the link 81 is urged by the spring 80 to push the long hole portion 78 of the valve rod 74, so that the valve rod 74 is moved in the direction of compressing the spring 79. As shown in FIG. 1, the flow path forming part 72 c of the first exhaust valve 72 of the exhaust valve 7 is moved to the position facing the outer opening 23 a and the inner opening 23 b of the striking cylinder exhaust port 23, so that the striking cylinder exhaust port 23 is opened. Also, the second exhaust valve 73 is moved to the upper side of the inner opening 32 b of the combustion chamber exhaust port 32 in conjunction with the first exhaust valve 72, so that the inner opening 32 b and the outer opening 32 a of the combustion chamber exhaust port 32 communicate with each other therebetween by the exhaust flow path forming cylinder 76 and the combustion chamber exhaust port 32 is opened. Thereby, the striking cylinder 2 and the combustion chamber 3 are opened to the atmosphere.

Also, the head valve 4 is pressed by the spring 44 and is thus in the state where the valve surface 40 is in contact with the partitioning part 50, i.e., in the state where the striking cylinder inlet 51 is closed by the head valve 4. In this state, the head valve inlet 53 is coupled to the actuation space 52.

When the contact member 8 is pressed to a material to be struck, the link 81 is rotated in a direction of extending the spring 80, so that the valve rod 74 is moved in the extension direction of the spring 79 in conformity to the rotation of the link 81 and the movement of the contact member 8 is transmitted to the exhaust valve 7 by the link 81.

As shown in FIG. 4, the sealing part 72 a of the first exhaust valve 72 of the exhaust valve 7 is moved to the position facing the outer opening 23 a and the inner opening 23 b of the striking cylinder exhaust port 23, so that the striking cylinder exhaust port 23 is closed. Also, the second exhaust valve 73 is moved between the outer opening 32 a and the inner opening 32 b of the combustion chamber exhaust port 32 in conjunction with the first exhaust valve 72, so that the combustion chamber exhaust port 32 is closed. Thereby, the striking cylinder 2 and the combustion chamber 3 are sealed.

Also, an air valve and a fuel valve (not shown) are opened in conjunction with the contact member 8 and an operation of the operation trigger 16, so that the gasified fuel and the compressed air are supplied to the combustion chamber 3. For example, when the contact member 8 is pressed to the material to be struck, the fuel valve (not shown) is opened, and when the operation trigger 16 is operated, the air valve (not shown) is opened. In the meantime, when the contact member 8 is pressed to the material to be struck and the operation trigger 16 is operated, the air valve and fuel valve (not shown) may be opened at predetermined timings. Also, when the contact member 8 is pressed to the material to be struck, the air valve and fuel valve (not shown) may be opened at predetermined timings.

When the compressed air is supplied to the combustion chamber 3, a pressure in the combustion chamber 3 rises. During the pressure rise in the combustion chamber 3 by the compressed air, the head valve 4 is pressed by the spring 44, so that the valve surface 40 is kept in the contact state with the partitioning part 50 and the striking cylinder inlet 51 is closed by the head valve 4. Therefore, even when the pressure in the combustion chamber 3 rises by the supply of the compressed air, the pressure does not rise in the striking cylinder 2 and the piston 21 is not actuated.

When the contact member 8 is pressed to the material to be struck, the operation trigger 16 is operated to open the air valve and the fuel valve (not shown) and the ignition device 31 is then actuated at a predetermined timing, the mixed gas of compressed air and fuel in the combustion chamber 3 is combusted. When the mixed gas is combusted in the combustion chamber 3, the pressure in the combustion chamber 3 rises and the high temperature and high pressure gas is introduced from the head valve inlet 53 of the head support member 5 into the actuation space 52.

When the pressure in the actuation space 52 rises, the high temperature and high pressure gas is applied to the actuation surface 43 of the head valve 4, so that the head valve 4 is moved upward with compressing the spring 44. Here, when the pressure in the actuation space 52 rises, the pressure is applied to the surface of the first seal part 41 facing the actuation space 52, too. However, since an area of the actuation surface 43 is larger, the head valve 4 is moved upward with compressing the spring 44.

As shown in FIG. 7, when the head valve 4 is moved upward, the striking cylinder inlet 51 is opened and the head valve inlet 53 is coupled to the striking cylinder inlet 51. Thereby, the high temperature and high pressure gas is introduced from the combustion chamber 3 into the striking cylinder 2 via the striking cylinder inlet 51, so that the pressure of the striking cylinder 2 rises.

When the pressure of the striking cylinder 2 rises, the piston 21 is pushed to move the piston 21 and the driver 20 in a direction of striking out a fastener, so that a fastener striking operation is performed. When the piston 21 and the driver 20 are moved in the direction of striking out a fastener, the gas (air) in a piston lower chamber 25 a, which is one of chambers in the striking cylinder 2 partitioned by the piston 21, flows from the inlet/outlet 60 into the blowback chamber 6. Also, since the piston 21 passes through the inlet/outlet 60 with compressively deforming the buffer material 22, a part of the high temperature and high pressure gas having driven the piston 21 is introduced into the blowback chamber 6.

When the gas (air) in the striking cylinder 2 flows into the blowback chamber 6 and the pressure in the blowback chamber 6 rises, the exhaust piston 71 of the exhaust valve 7 is pushed, as shown in FIG. 5. In the state where the exhaust valve 7 and the link 81 are coupled via the long hole portion 78 formed in the valve rod 74 and the position of the link 81 is fixed by the contact member 8, the link 81 and the valve rod 74 are decoupled, so that the exhaust valve 7 can move to the position at which it is to collide with the buffer material 77. Since a moving amount of the exhaust valve 7 is restrained by the buffer material 77, the durability of the exhaust valve 7 is improved.

Thereby, when the exhaust piston 71 of the exhaust valve 7 is pushed, the first exhaust valve 72 is moved to the position at which the flow path forming part 72 c faces the outer opening 23 a and the inner opening 23 b of the striking cylinder exhaust port 23, so that the striking cylinder exhaust port 23 is opened. Also, the second exhaust valve 73 is moved to the upper side of the inner opening 32 b of the combustion chamber exhaust port 32 in conjunction with the first exhaust valve 72, so that the inner opening 32 b and the outer opening 32 a of the combustion chamber exhaust port 32 communicate with each other therebetween by the exhaust flow path forming cylinder 76 and the combustion chamber exhaust port 32 is opened.

Therefore, the striking cylinder 2 and the combustion chamber 3 are opened to the atmosphere, and the gas in the combustion chamber 3 is exhausted from the combustion chamber exhaust port 32 to the outside. Also, the high temperature and high pressure gas flows from the combustion chamber 3 into the striking cylinder 2 through the striking cylinder inlet 51 and the pressure in the combustion chamber 3 is thus lowered, so that the head valve 4 is pressed with the spring 44 and is moved to the position at which the valve surface 40 is in contact with the partitioning part 50, and the striking cylinder inlet 51 is closed by the head valve 4.

When the piston 21 and the driver 20 are further moved in a direction of striking out a fastener and the piston 21 is moved to the bottom dead point and collides with the buffer material 22, the piston 21 and the driver 20 intend to move upward by the elasticity of the buffer material 22. When the piston 21 is moved to the upper side of the inlet/outlet 60 through the inlet/outlet 60, the gas (air) in the blowback chamber 6 of which the pressure has risen is introduced into the striking cylinder 2 and pushes the piston 21. When the piston 21 is pushed, the gas in a piston upper chamber 25 b, which is the other chamber in the striking cylinder 2 partitioned by the piston 21, is exhausted from the striking cylinder exhaust port 23 to the outside, and the piston 21 and the driver 20 are returned to the top dead point.

When the contact member 8 separates from the material to be struck, the link 81 is urged by the spring 80 to push the long hole portion 78 of the valve rod 74, so that the valve rod 74 is moved in the direction of compressing the spring 79. Thereby, as shown in FIG. 1, the state where the first exhaust valve 72 opens the striking cylinder exhaust port 23 and the second exhaust valve 73 opens the combustion chamber exhaust port 32 is kept.

<Operational Effect Example of Nailing Machine of Embodiment>

In the nailing machine 1A of the embodiment, the compressed air and the fuel are supplied to the combustion chamber 3, the mixed gas is combusted to generate the high pressure gas and the piston 21 of the striking cylinder 2 is pushed by the high pressure gas, so that the force of pushing a fastener by the piston 21 and the driver 20 increases.

Thereby, it is possible to increase an output for striking a fastener, as compared to the related-art gas combustion type nailing machine in which the ordinary pressure gas is used.

Also, the head valve 4 configured to open and close the striking cylinder inlet 51 between the combustion chamber 3 and the striking cylinder 2 is provided, so that it is possible to disable the striking cylinder 2 from actuating even though the compressed air is just supplied to the combustion chamber 3. Also, the head valve 4 is actuated by the combustion pressure of the mixed gas, so that it is not necessary to provide a separate drive source for driving the head valve 4. Thereby, it is possible to simplify structures of the head valve 4 and the drive mechanism thereof, to miniaturize the device and to save the cost.

In the configuration where the head valve 4 is actuated by the combustion pressure of the mixed gas, when the high temperature and high pressure gas flows from the combustion chamber 3 into the striking cylinder 2 through the striking cylinder inlet 51 and the pressure in the combustion chamber 3 is thus lowered, the striking cylinder inlet 51 is closed by the head valve 4. For this reason, while the piston 21 returns from the bottom dead point position to the top dead point position, it is not possible to exhaust the gas in the striking cylinder 2 from the combustion chamber 3 to the outside.

Therefore, the striking cylinder exhaust port 23 configured to communicate the striking cylinder 2 and the outside and the first exhaust valve 72 configured to open and close the striking cylinder exhaust port 23 are provided. The striking cylinder exhaust port 23 is provided to face the top dead point position of the piston 21.

Thereby, even when the striking cylinder inlet 51 is closed by the head valve 4 and communication between the striking cylinder 2 and the combustion chamber 3 is thus closed, while the piston 21 returns from the bottom dead point position to the top dead point position, it is possible to exhaust the gas in the striking cylinder 2 from the combustion chamber 3 to the outside. Therefore, it is possible to securely return the piston 21 to the top dead point position.

Also, the combustion chamber exhaust port 32 configured to communicate the combustion chamber 3 and the outside and the second exhaust valve 73 configured to open and close the combustion chamber exhaust port 32 are provided, so that it is possible to exhaust, to the outside, the gas remaining in the combustion chamber 3 after actuating the piston 21 of the striking cylinder 2.

Also, the exhaust valve 7 is configured so that the first exhaust valve 72 configured to open and close the striking cylinder exhaust port 23 and the second exhaust valve 73 configured to open and close the combustion chamber exhaust port 32 provided to the combustion chamber 3 are to operate in conjunction with each other. Thereby, it is possible to open the striking cylinder exhaust port 23 and the combustion chamber exhaust port 32 at predetermined timings. In the embodiment, the first exhaust valve 72 and the second exhaust valve 73 are integrally coupled by the valve rod 74, so that it is possible to open the striking cylinder exhaust port 23 and the combustion chamber exhaust port 32 without delay of actuation timing between the first exhaust valve 72 and the second exhaust valve 73.

Also, the exhaust valve 7 is provided at one side part of the striking cylinder 2 with respect to the extension direction of the handle part 11. Thereby, as compared to a configuration where the exhaust valve 7 is provided between the striking cylinder 2 and the handle part 11, which is the rear side of the striking cylinder 2, it is possible to shorten a distance between the striking cylinder 2 and the handle part 11. Therefore, a distance L1 between a driver center P1 of the striking cylinder 2 and an operation position P2 of the operation trigger 16 is shortened to improve the operability. Also, as compared to a configuration where the exhaust valve 7 is provided at a front side of the striking cylinder 2, it is possible to shorten a distance L2 between a front surface P3 of the main body part 10 and the driver center P1 of the striking cylinder 2, so that it is possible to perform a striking operation at a narrow place such as the vicinity of a wall surface, and to improve the corner striking performance.

In the embodiment, the exhaust valve 7 configured to open and close the striking cylinder exhaust port 23 and the combustion chamber exhaust port 32 is actuated by the gas supplied to the blowback chamber 6. However, the drive source of the exhaust valve 7 is not limited to the gas actuation. Also, in the embodiment, the air is used as the oxidant, and the mixed gas of the compressed air as the compressed oxidant and the fuel is used for actuation. However, the oxidant is not limited to the compressed air and the other oxidants may be used inasmuch as the oxidant contains oxygen necessary for combustion of the fuel. For example, oxygen, ozone, nitrogen monoxide and the like may also be used, instead of the air.

1A . . . nailing machine, 10 . . . main body part, 11 . . . handle part, 12 . . . nose part, 13 . . . tank mounting part, 14 . . . magazine, 15 . . . air plug, 16 . . . operation trigger, 17 . . . battery, 18 . . . battery mounting part, 2 . . . striking cylinder (striking mechanism), 2 a . . . piston position restraint part, 20 . . . driver, 21 . . . piston, 21 a . . . piston ring, 22 . . . buffer material, 23 . . . striking cylinder exhaust port(the exhaust port), 23 a . . . outer opening, 23 b . . . inner opening, 24 . . . spring receiving part, 25 a . . . piston lower chamber (one chamber), 25 b . . . piston upper chamber, 3 . . . combustion chamber, 30 . . . head part, 31 . . . ignition device, 32 . . . combustion chamber exhaust port (exhaust port), 32 a . . . outer opening, 32 b . . . inner opening, 4 . . . head valve (valve member), 40 . . . valve surface, 41 . . . first seal part, 41 a . . . first seal material, 42 . . . second seal part, 42 a . . . second seal material, 43 . . . actuation surface, 44 . . . spring, 45 . . . concave part, 5 . . . valve support member, 50 . . . partitioning part, 51 . . . striking cylinder inlet, 52 . . . actuation space, 53 . . . head valve inlet, 54 . . . buffer material, 6 . . . blowback chamber, 60 . . . inlet/outlet, 7 . . . exhaust valve, 71 . . . exhaust piston, 72 . . . first exhaust valve (striking cylinder exhaust valve), 72 a . . . sealing part, 72 b . . . sealing part, 72 c . . . flow path forming part, 73 . . . second exhaust valve (combustion chamber exhaust valve), 73 a . . . sealing member, 74 . . . valve rod, 74 a . . . spring retainer, 75 . . . exhaust cylinder, 76 . . . exhaust flow path forming cylinder, 76 a . . . wall part, 77 . . . buffer material, 78 . . . long hole portion, 79 . . . spring, 8 . . . contact member, 80 . . . spring, 81 . . . link 

1. A driving tool comprising: a striking cylinder including a piston configured to be actuated by a combustion pressure of a mixed gas of compressed oxidant and fuel; a combustion chamber in which the mixed gas of compressed oxidant and fuel is to be combusted; a valve member configured to open and close communication between the striking cylinder and the combustion chamber; and a striking cylinder exhaust valve configured to open and close communication between the striking cylinder and an outside.
 2. The driving tool according to claim 1, further comprising: a combustion chamber exhaust valve configured to open and close communication between the combustion chamber and the outside.
 3. The driving tool according to claim 2, wherein an operation of opening and closing the striking cylinder exhaust valve and an operation of opening and closing the combustion chamber exhaust valve are performed in conjunction with each other.
 4. The driving tool according to claim 3, wherein the striking cylinder exhaust valve and the combustion chamber exhaust valve are integrally formed.
 5. The driving tool according to claim 1, further comprising: a main body part including the striking cylinder and the combustion chamber; and a handle part extending from the main body part, wherein the striking cylinder exhaust valve is provided at one side part of the striking cylinder with respect to an extension direction of the handle part.
 6. The driving tool according to claim 5, wherein the striking cylinder exhaust valve is configured to be actuated by axial movement of the striking cylinder.
 7. The driving tool according to claim 2, further comprising: a main body part including the striking cylinder and the combustion chamber, and a handle part extending from the main body part, wherein the striking cylinder exhaust valve is provided at one side part of the striking cylinder with respect to an extension direction of the handle part, and the combustion chamber exhaust valve is provided at one side part of the combustion chamber with respect to the extension direction of the handle part.
 8. The driving tool according to claim 7, wherein the striking cylinder exhaust valve and the combustion chamber exhaust valve are configured to be actuated by axial movement of the striking cylinder.
 9. The driving tool according to claim 1, wherein the striking cylinder exhaust valve includes a striking cylinder exhaust port provided at a top dead point position of the piston and configured to communicate the outside and an inside of the striking cylinder. 